US-12621724-B2 - Apparatus and method for improving handover performance in wireless communication system

US12621724B2US 12621724 B2US12621724 B2US 12621724B2US-12621724-B2

Abstract

A baseband circuit that receives, from a RFIC, and being configured to process, a signal including a plurality of synchronization signal blocks generated in a neighbor cell and a signal including radio resource control parameters generated in a serving cell, includes: a storage; a controller configured to write/read data to/from the storage; and a signal processor controlled by the controller, wherein the controller sets a number of measurement target SSBs based on the RRC parameters, wherein the signal processor checks a validity of the set number of SSBs, and the controller stores valid SSB information in the storage based on the checking result, verifies a number of valid SSBs based on the stored valid SSB information, and controls the signal processor or invalidates the neighbor cell so that the signal processor measures reference signal received power of the neighbor cell based on a verification result.

Inventors

Dahae CHONG
Joohyun DO

Assignees

SAMSUNG ELECTRONICS CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230808
Priority Date: 20200709

Claims (14)

1 . A method performed by a terminal in a wireless communication system having a plurality of cells including a serving cell and a neighbor cell, the method comprising: receiving a radio resource control (RRC) parameter from the serving cell; receiving a plurality of synchronization signal blocks (SSBs) generated in the neighbor cell, wherein each of the SSBs generated in the neighbor cell is transmitted from a respective beam formed by the neighbor cell; setting, based on the RRC parameter, at least one measurement target SSB among the plurality of SSBs, a number of the measurement target SSBs being limited to a maximum assignable number per frequency band as specified by the RRC parameter; decoding a physical broadcast channel (PBCH) of an SSB among the at least one measurement target SSB, and when the decoding is successful, determining the SSB to be valid and measuring reference signal received power (RSRP) of the neighbor cell based on the valid SSB for use in a handover determination; and when a decoding of a PBCH of each of the at least one measurement target SSB is unsuccessful, invalidating the neighboring cell for the handover determination.
2 . The method of claim 1 , further comprising: determining whether an m th SSB of the serving cell is turned on, where m is an integer of one or more, and when the m th SSB of the serving cell is determined to be turned on, determining that an n th SSB of the plurality of SSBs generated in the neighbor cell, corresponding to the m th SSB of the serving cell, is valid without decoding the PBCH of the n th SSB, where n is an integer of one or more; and when the n th SSB is determined to be valid, measuring RSRP of the neighbor cell.
3 . The method of claim 2 , wherein when the m th SSB of the serving cell is determined to be turned off, decoding the PBCH of the n th SSB.
4 . The method of claim 1 , comprising decoding a PBCH of each of the at least one measurement target SSB, and measuring RSRP of the neighbor cell when the decoding of the PBCH of at least one SSB among the at least one measurement target SSB is successful.
5 . The method of claim 4 , wherein: the at least one measurement target SSB is a plurality of measurement target SSBs; and the measuring of the RSRP of the neighbor cell comprises measuring RSRP of each of the measurement target SSBs for which decoding is successful.
6 . The method of claim 4 , wherein a maximum RSRP among measured RSRPs of SSBs for which decoding is successful is used as the measured RSRP of the neighbor cell.
7 . The method of claim 4 , wherein an average value of measured RSRPs of SSBs for which decoding is successful is used as the measured RSRP of the neighbor cell.
8 . The method of claim 1 , wherein: each of the SSBs generated in the neighbor cell includes a primary synchronization signal (PSS), a secondary synchronization signal (SSS), and a PBCH.
9 . A terminal in a wireless communication system having a plurality of cells including a serving cell and a neighbor cell, the terminal comprising: memory; at least one processor configured to execute instructions read from the memory to: receive a radio resource control (RRC) parameter from the serving cell; receive a plurality of synchronization signal blocks (SSBs) generated in the neighbor cell, wherein each of the SSBs generated in the neighbor cell is transmitted from a respective beam formed by the neighbor cell; set, based on the RRC parameter, at least one measurement target SSB among the plurality of SSBs, a number of the measurement target SSBs being limited to a maximum assignable number per frequency band as specified by the RRC parameter; decode a physical broadcast channel (PBCH) of an SSB among the at least one measurement target SSB, and when the decoding is successful, determine the SSB to be valid and initiate a reference signal received power (RSRP) measurement of the neighbor cell based on the valid SSB for use in a handover determination; and when a decoding of a PBCH of each of the at least one measurement target SSB is unsuccessful, invalidate the neighboring cell for the handover determination.
10 . The terminal of claim 9 , wherein the at least one processor is further configured to: determine whether an m th SSB of the serving cell is turned on, where mis an integer of one or more, and when the m th SSB of the serving cell is determined to be turned on, determine that an n th SSB of the plurality of SSBs of the neighbor cell, corresponding to the m th SSB of the serving cell, is valid without decoding the PBCH of the n th SSB, where n is an integer of one or more; and when the n th SSB is determined to be valid, measure RSRP of the neighbor cell.
11 . The terminal of claim 10 , wherein when the m th SSB of the serving cell is determined to be turned off, the at least one processor decodes the PBCH of the n th SSB.
12 . The terminal of claim 9 , wherein the at least one processor decodes a PBCH of each of the at least one measurement target SSB, and initiates RSRP measurement of the neighbor cell when the decoding of the PBCH of at least one SSB among the at least one measurement target SSB is successful.
13 . The terminal of claim 12 , wherein: the at least one measurement target SSB is a plurality of measurement target SSBs; and the measuring of the RSRP of the neighbor cell comprises measuring RSRP of each of the measurement target SSBs for which decoding is successful.
14 . The terminal of claim 13 , wherein one of a maximum RSRP among measured RSRPs of SSBs for which the decoding is successful, or an average value of the measured RSRPs of SSBs for which the decoding is successful, is used as the measured RSRP of the neighbor cell.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is a divisional under 35 U.S.C. 120 of U.S. patent application Ser. No. 17/226,674, filed Apr. 9, 2021, which is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2020-0084939, filed on Jul. 9, 2020, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entireties. TECHNICAL FIELD This disclosure relates generally to wireless communications and more particularly to improving handover performance in a wireless communication system. DISCUSSION OF THE RELATED ART To meet the increasing demand for wireless data traffic since the commercialization of fourth generation (4G) communication systems, efforts have been made to develop and commercialize an improved fifth generation (5G) communication system, also known as a New Radio (NR) system. To achieve a high data rate, the 5G communication system may be implemented with capability for millimeter (mm) wave band operations (for example, around 28 GHz or 60 GHz). To reduce a path loss of radio waves in a mmWave band and increase a propagation distance of radio waves, in the 5G communication system, beamforming, massive multiple-input and multiple-output (MIMO), full dimensional (FD) MIMO (FD-MIMO), an array antenna, analog beam-forming, large scale antenna technology, or the like have been or will be applied. In addition, to improve wireless communication system networks, in the 5G communication system, technology such as an evolved small cell, an advanced small cell, a cloud radio access network (cloud radio access network (RAN)), an ultra-dense network, device to device (D2D) communication, wireless backhaul, a moving network, cooperative communication, coordinated multi-points (CoMP), and interference cancellation have been or will be applied. Further, with 5G, an advanced coding modulation (ACM) method, such as “hybrid frequency shift keying and quadrature amplitude modulation (FQAM)” and sliding window superposition coding (SWSC), and advanced access technology such as filter bank multi carrier (FBMC) and sparse code multiple access (SCMA), or the like have been or will be applied. In advanced wireless communication systems, a terminal may measure reference signal received power (RSRP) of a neighbor cell, which is a cell located near a serving cell to which the terminal is communicatively connected. The RSRP measurement result may be used to determine whether handover to the neighbor cell is appropriate. The terminal may transmit the measurement result to the serving cell as a measurement report. The serving cell may then transmit the measurement report to a core network, and the core network may determine whether the handover should occur based on the measurement report transmitted from the serving cell as well similar measurement reports from neighbor cells). The core network may transmit the handover determination result to the serving cell and the relevant neighbor cell. Each of the cells may then be involved in coordinating the handover. However, depending on the situation, when measuring RSRP of the neighbor cell, there is an issue that certain signals transmitted by the serving cell may produce a large interference. In this scenario, RSRP measurement accuracy may deteriorate, which may lead to unnecessary handover of the terminal. Such unnecessary handover may degrade the modem performance of the terminal and excessively consume network resources. SUMMARY Embodiments of the inventive concept provide an apparatus and method for improving handover performance and stability by reducing unnecessary handovers. According to an aspect of the inventive concept, there is provided a baseband circuit receiving, from a radio frequency integrated circuit (RFIC), and being configured to process, a signal including a plurality of synchronization signal blocks (SSBs) generated in a neighbor cell among a plurality of cells and a signal including radio resource control (RRC) parameters generated in a serving cell among the plurality of cells, including: a storage; a controller configured to write or read data to or from the storage; and a signal processor controlled by the controller, wherein the controller sets a number of measurement target SSBs among the plurality of SSBs based on the RRC parameters, the signal processor checks a validity of the set number of SSBs, and the controller stores valid SSB information in the storage based on the checking result, checks a number of valid SSBs based on the stored valid SSB information, and controls the signal processor or invalidate the neighbor cell so that the signal processor measures reference signal received power (RSRP) of the neighbor cell based on a result of the checking. According to another aspect of the inventive concept, there is provided a terminal receiving a plurality of synchronization signal blocks (SSBs) from a neighbor cell among a plurality of cells, the